The code does nothing to force developers to build 50 story apartment buildings, it simply allows developers to build 50 story apartment buildings. Hollywood is, as he notes, a bit scruffy, but it is also adjacent to some very expensive real estate, with the Hollywood Hills to the north, Hancock Park to the south and West Hollywood to the west. It also features two subway stops on a subway line that has pretty decent ridership. It is entirely possible that market forces would lead developers to increase its density, were they allowed to do so. These market forces also reflect preferences.